Some of the most vexed problems of the present day will soon be solved by aerial navigation. Take that of our overcrowded cities. Everybody knows how first the trolley car and then the automobile helped to relieve the congestion of towns by making it feasible for people to live many miles from the scenes of their daily work, but at the same time seriously swelled the traffic of the streets in business quarters. Aircraft will bring far greater improvements in this respect, without corresponding disadvantages. In a few years it will probably be no inconvenience to live fifty or a hundred miles from one’s place of business. Aeroplanes, built for carrying several passengers in perfect comfort, already fly at speeds of from 120 to 150 miles an hour, and are almost independent of weather. Much greater speeds will doubtless be common in the future. Automobiles, all running on the same level, have almost reached the limit of space available in our busiest streets, and, under such conditions, they have nearly lost the advantage of speed they once possessed over the obsolete horse-drawn vehicle. There can never be such crowding in the air. When a great volume of aerial traffic is concentrated toward the centers of towns, people will fly their vehicles at various prescribed levels, and probably “park” them on many-storied landing stages. New methods of landing will undoubtedly be invented. The device known as the “helicopter,” which has made progress toward the practical stage during the past year, points out the possibilities in this direction. In the helicopter the propeller blades revolve around a vertical shaft, thus permitting the vehicle to rise or descend vertically. A prize of $100,000 has recently been offered by M. Michelin, the well-known French patron of aviation, for the perfection of this device, which may soon revolutionize the design of flying machines.
Mr. Holt Thomas, the Englishman whose foresight and enthusiasm have done so much to hasten the arrival of practical commercial aeronautics, believes that in the near future the main airways of the world will be served by airships rather than by aeroplanes. For long journeys the airship has the advantage that it can carry an ample supply of fuel without encroaching too much upon the space available for passengers and cargo. It is, therefore, especially suitable for transoceanic journeys. Hitherto airships, when not in flight, have been housed in enormous hangars, involving heavy cost of installation and their landing has required the services of hundreds of men—an operation that will probably seem laughable in its crudity to the next generation. The airship of the future will probably never go into a hangar at all except for occasional overhauling, as an ordinary ship goes into drydock. Hence only a few of these costly structures will be needed. While in service the airship will, on reaching an air port, moor herself at the bow to a great steel tower, and swing with the wind as a marine vessel swings at her anchor. At the top of the tower there will be a landing stage for passengers and freight, connected by lifts with the ground below. From the main air ports, thus equipped, will radiate minor air routes, served by aeroplanes, and, in some cases, by flying boats.
Such landing places for airships were predicted by Kipling in his “With the Night Mail”—but the author’s vista was of the year 2000! We are not traveling so slowly as that. Consider what it means that the world heard with bated breath of Blériot’s flight over the English Channel in 1909; and just ten years later men had flown over the Atlantic Ocean.
We have been writing of the future; but we need not look ahead for illustrations of the practical value of aerial navigation. Useful feats already accomplished are so astonishing in their variety that they make one cautious about assigning a limit to the possible applications of the new art. It has happened, for example, that a man who had booked passage on a trans-Pacific steamer missed his boat at Seattle; whereupon he hired an aeroplane, at a cost of $75, and overtook the steamer on her way down Puget Sound, thus saving some weeks of delay in waiting for the next one. Another man, who produces honey on a large scale, found that spray-poisoned orchards were playing havoc with his bees. He traveled in an aeroplane over the surrounding country, selecting stands for his hives at safe distances from such orchards, and he estimates that this precaution saved him $10,000 in a single year. In August, 1919, a flying boat deposited a bag of mail on the White Star liner Adriatic two hours after the ship had left New York.
Several aerial mail routes are now in operation on both sides of the Atlantic. The first regular service of this character in America was begun May 15, 1918, between New York and Washington, and during the first year carried 7,720,840 letters, with few accidents and no fatalities. The first year of service cost the Government $137,900, and the sale of aeroplane mail stamps during the same period yielded a revenue of $159,700. Out of 1,261 possible trips on this route, 1,206 were undertaken, and only fifty-five were abandoned on account of unfavorable weather. During 1919 the Post Office Department not only established other aerial routes, but relegated the aerial mail service to the ranks of the commonplace by reducing the postage on letters carried by aeroplane to the ordinary first-class rate of two cents an ounce.
In Europe lines of fast aeroplanes carrying mails, passengers, and freight daily over regular routes are becoming part of the established order of things. The operators of a line between London and Paris, which was inaugurated in November, 1919, are now planning to establish an hourly service. Some of these lines have been equipped with wireless telephony, so that the pilots can keep in constant communication with numerous stations of the company along the route, and also with one another. They are thus able to obtain, among other things, current information about the prevalence of fog or other atmospheric conditions at points ahead of them. Presumably the passengers who patronize the aeroplane express will also, eventually, enjoy the use of the wireless telephone en route. In connection with the new air routes suitable landing grounds, for regular or emergency use, are being laid out at short intervals; the ideal aimed at, for the present, being the so-called “ten-mile chain”; i. e., a series of emergency landing grounds about ten miles apart. From ordinary flying levels a pilot on such a route can always glide to one of these grounds in case his motor fails. The landing grounds will be utilized, under certain restrictions, for grazing cattle and for agricultural purposes, to help cover the cost of rental and maintenance. During 1919 the British Government established a chain of landing grounds in Africa, all the way from Cairo to the Cape.
One of the developments of the war was the use of aeroplanes for photographic mapping. The aeroplane flies over a long tract of ground, and the camera, exposed vertically, takes pictures automatically at fixed intervals. The pictures thus taken are carefully joined together in a single strip. A second tract, parallel with the first, is photographed in the same manner, and so on, until the whole area has been covered. Eventually all the pictures are assembled to form a so-called “mosaic.” This process is highly successful for mapping a flat country, but presents difficulties when there are hills and mountains. Some sort of stereoscopic process will probably be perfected for depicting accurately differences in level and producing a “contoured” map. Although aeronautical mapping does not yet replace old-fashioned methods, it already has several obvious uses. It is especially suitable for the revision of existing maps. Thus the plan of a city can be quickly brought up to date by this process. In the United States the Geological Survey has been engaged for many years in producing large-scale topographic maps of all parts of the country. This work proceeds slowly, and some of the maps are ten or fifteen years old. The contours and other natural features on such a map are still correct, but changes in the region due to the work of man are often extensive. Revision of these features can easily be made by the method above described.
For the preliminary mapping of a new country, by photography or by hand, the aeroplane offers the means of saving an immense amount of time and effort. The surveyor no longer needs to cut tracks through the jungle or scale mountains. No region is very difficult of access to the aviator. The summit of Mount Everest, the highest mountain in the world, is actually a mile lower than the greatest altitude attained by an aeroplane. Aviation has become an important feature of exploring expeditions. Captain Amundsen, the polar explorer, qualified as an air pilot before he embarked on his drift across the North Polar basin, and took aeroplanes with him on that journey. In India the Survey Department has organized a regular aerial photographic and reconnoissance service, and has lately photographed the high waters of the River Sutlej in order to obtain data for a big electrification project. Photographs of the Nile country have also been made for hydrological purposes. British aviators in Mesopotamia have mapped the flood boundaries of the Tigris and provided data for estimating crop areas. In the Philippines an engineer recently made a long aeroplane flight to determine which of three general routes was most suitable for a new railway. Many months of time and thousands of dollars were thus saved, as it was only necessary to send out one party of locating engineers instead of three after the selection had been made.
Recently the aerial surveyor has become the rival of the hydrographer in mapping shoals, channels, submerged rocks, and other features beneath the water. If the water is clear and suitable atmospheric conditions prevail, objects submerged to a considerable depth may be distinctly seen from an aeroplane flying far above the surface. It was on account of this fact that Allied aviators were able to spot submerged German submarines during the World War. The camera, equipped with proper plates and ray filters, can pierce the water even better than the eye. Thus objects have been photographed at a depth of more than 50 feet. British aviators charted the harbor of Rahbeg, on the coast of Arabia, by the process in 1917. In this country the leading exponent of underwater photography is Dr. Willis T. Lee, of the United States Geological Survey, who has taken scores of photographs showing submerged features of the waters adjacent to Chesapeake Bay. It is likely that rivers like the Mississippi, with ever shifting sand bars, will soon be made safe by monthly or weekly mapping from the air. In earthquake regions, such as southern Italy and Japan, the changing coast lines, shallows and harbors can easily be photographed after each new quake, thus keeping navigation open and protecting the lives of mariners.
Another application of this process of sighting submerged objects from the air is the aerial fish patrol. The plan of using aircraft to locate schools of fish appears to have been first suggested by Professor Joubin, of the Oceanographic Institute of Monaco, and it has been carried out with much success in both Europe and America. Its promoters hope that it will eventually revolutionize the fishing industry and add greatly to the world’s food supply. In the year 1919 seaplanes from the North Island Air Station at San Diego, California, made regular flights at an altitude of about 500 feet over the adjacent waters as an adjunct to the important fisheries in that vicinity. When a school of fish was detected, the aviator dropped low enough to ascertain the species, and if it proved to be of a commercial kind, such as the sardine, the news was flashed by wireless to the fishing fleet. The ocean in the neighborhood of San Diego was divided into numbered squares, shown on charts, and locations were reported by number. In 1920 a daily patrol was maintained by Navy seaplanes over the waters of Chesapeake Bay in behalf of the menhaden fishery. According to an official report, “the experiments fully demonstrated the commercial value of planes in this fishery.” It is believed that aircraft might be used with equal success in connection with the whaling industry.